I dont really know the answer to your question but i will tell you this. If you are sticking with a stock ratio (something commonly found) then buy the time you buy the parts and have the gears set you will be better off buying a entire axle and just swapping them out.
even if you buy the parts used you still are going to have to have a master install kit and have to have the gears set....around here you are talking 150 to have them set plus 60 bucks at least for the install kit....